1. Field of the Invention
The invention relates to a composite material between different types of members, a method for producing it, and a sliding material made of the composite material.
2. Description of the Related Art
With the development of industrial technologies in these years, demands are increasing for a material which provides a plurality of functions which cannot be provided by a single material, e.g., a composite material which is produced by laminating and bonding two materials having different properties. To produce a composite material by combining two different types of metal materials, a hot rolling method (e.g., cladding) or a liquid metal solidifying method (e.g., a casting method) can be applied. And, a relatively good bond strength can be obtained by such a manufacturing method.
Demands for the properties of a compound material are increasing in complexity, and there is a demand for combining different materials, e.g., a metal material and a resin material. But, the production of a composite material by laminating a metal material and a resin material has a disadvantage that it is difficult to obtain a sufficient bond strength by a complex method which has been used to produce a composite material of metal materials. Specifically, when different metal materials are bonded by a liquid metal solidifying method, a diffusional reaction takes place because the metal materials are mutually bonded, causing mechanical bonding and physical or chemical bonding. But, when a metal material and a resin material are bonded, it is very hard to obtain a satisfactory bond strength because a chemical bond effect is not obtained between the metal material and the resin material.
When a metal material and a resin material are bonded under conditions of a high temperature and a high pressure, a stress is caused on a bonded interface due to a difference of coefficient of thermal expansion between these materials and they must be kept under such conditions for a long duration, resulting in disadvantages of increasing the production cost or the like.
When a composite material is made of a metal material and a resin material, an adhesive may be used to bond them. But, it is not easy to choose an appropriate adhesive which has good adhesive properties for both metal and resin materials, and since a resin-based adhesive has a metal-resin bonded interface, a bond strength between the metal material and the resin material cannot be improved basically. And, as a method to improve an interface strength when two types of members are bonded, it is known to increase a bonded area by enlarging the surface area by honing or chemical etching. But, the increase of a bonded area by honing or chemical etching is limited, and a resistance against a shearing breakaway of the interface and a tensile stress in a perpendicular direction to the bonded interface is small, so that a bond strength between different types of materials cannot be enhanced sufficiently.
As described above, in the case of a conventional composite material and a method for manufacturing it, when different materials such as a metal material and a resin material are mutually laminated and bonded, a sufficient bond strength cannot be obtained. And, the resin material is deteriorated, and the production cost is increased.
Therefore, a composite material which is produced by combining different types of materials such as a metal material and a resin material is demanded to have improved reliability between the different types of materials by improving a bond strength between the different types of materials without involving deterioration of the resin material or degradation of the strength of the composite material itself.
The present invention has been completed to remedy the above-described disadvantages and aims to provide a composite material which can improve a bond strength between different types of materials without involving deterioration of a resin material or degradation of the strength of the composite material itself.
A first composite material of the invention comprises a first member formed of a first material, an intermediate layer formed of a plate which is bonded to the first member and has a plurality of holes, and a second member formed of a second material different from the first member, wherein the second material is charged into the holes of the plate which forms the intermediate layer, and the holes in which the second material is charged have a shape to exert the resistance of the charged second material against a tensile stress applied in a direction perpendicular to the bonding surface of the first member.
And, each of the holes formed in the plate which forms the intermediate layer has a first opening on the side of the first member and a second opening on the side of the second member to communicate with the first opening, and forms a stepped passage which has a stepped portion formed by an overlapped area of the hole of the first member and the plate of the second member.
The second opening of the first composite material has an area smaller than that of the first opening.
Further, the plate which forms the intermediate layer has the communicating stepped passages each of which is formed of the second hole and the first hole having a larger diameter than the second hole and formed in a stepped shape in cross section by the first hole and the second hole.
More further, the plate is a bonded material of a first plate having the first holes and a second plate having the second holes with a diameter smaller than that of the first holes which are bonded with the second holes and the first holes aligned.
Or the plate is a bonded material of a first plate having the first holes and a second plate having the second holes with a diameter substantially the same as that of the first holes which are bonded with the first holes and the second holes partly overlapped. And, this bonded material has the first holes and the second holes in multiple numbers partly overlapped.
And, in the first composite material of the invention, the first member is made of a metal material, and the second member is one member selected from a group consisting of a resin material, a rubber material, and a glass material which have a hardening temperature lower than the melting point of the metal material.
A second composite material of the invention is a composite material comprising a first member, an intermediate layer formed of at least one layer bonded to the first member and having a large number of holes, and a second member formed on the intermediate layer, wherein the second member is made of a material different from the first member, and the material which forms the second member is charged into the holes of the intermediate layer. In this composite material, the intermediate layer comprises at least one structural member selected from a group consisting of a granular metal material and a fibrous metal material, and this structural member is formed into a three-dimensional network having voids by having the granular metal material and the fibrous metal material diffusion bonded partly and/or partly bonded by a metal having a melting point lower than that of a metal configuring the structural member.
The structural member which forms the second composite material has a porosity of 10% to 70%.
The granular metal material is spheres having an average diameter of 0.001 to 10 mm. And, the fibrous metal material is a cylindrical material having an average diameter of 0.001 to 10 mm.
In the second composite material, the first member is an Fe-based metal material, and the second member is one member selected from a group consisting of a resin material, a rubber material, and a glass material. The intermediate layer is at least one structural member selected from a group consisting of a granular metal material and a fibrous metal material, and this structural member is formed into a network structure having transmission holes which are formed of voids in the structural member by being bonded by a metal having a melting point lower than that of a metal mutually and partly configuring the structural member.
A method for producing a composite material of the invention, when the composite material is produced by laminating a first member and a second member formed of a material different from the first member, has a step to bond to the first member a member having holes which vary in stages or communication holes which make a detour to exert a resisting force against a tensile stress in a direction perpendicular to the surface of the first member to form an intermediate layer, and a step to laminate the second member to the first member while charging a portion of the second member into the transmission holes of the member which forms the intermediate layer.
In the composite material and the method for producing the composite material of the invention, it is particularly preferable that a metal material is used as the first member, and the second member is one member selected from a group consisting of a resin material, a rubber material, and a glass material which have a hardening temperature lower than the melting point of the metal material.
In the composite material and the method for producing the composite material of the invention, the intermediate layer in which a portion of the second member is charged is formed by bonding a member which has openings opened to the side of at least the second member to the first member, so that the strength of the intermediate layer itself and the bond strength between the first member and the intermediate layer can be improved. In addition, since the voids in which the second member is charged is formed of the holes, the voids charged with the second member can be formed in a large size. In other words, an amount of the second member charged into the intermediate layer can be increased.
And, the holes have a shape in such that the charged second member in the holes exert a resisting force against a shearing stress in a direction parallel to a bonded interface with the first member and a tensile stress in a direction perpendicular to the surface of the member, e.g., a shape having second openings which are formed on the side of the second member and first openings which have a space not overlapping with the second openings, or a shape having openings on the side of the second member with an area smaller than that of the openings on the side of the first member. The structural member is at least one member selected from a granular metal material and/or a fibrous metal material, and the structural member is formed into a three-dimensional network structure having voids of roundabout passages by being bonded mutually and partly by a metal having a melting point lower than that of a metal configuring the component member. Thus, when a resin material or a glass material is used for the second material, a bond strength of these materials to the first member can be enhanced, and reliability of the composite material between different types of materials can be improved remarkably.